Human erythrocyte acetylcholinesterase (Acetylcholine acetyl hydrolase,E~C.3.1.l.7.) was purified by 3000 fold with 10% yield. This purified material has a molecular weight greater than 1 x lOG. General kinetic properties of this purified enzyme are similar

to those of the starting material.

Meanwhile, Triton X lOOt a non-ionic detergent)-solubilised erythrocyte acetylcholinesterase preparations from different individuals were subjected to DEAE cellulose column chromatography and polyacrylamide gel elctrophoresis respectively. With the samples tested, four types of variants were obtained with DEAE cellulose column chromatography. Similarly, three types of variants were found if polyacrylamide gel electrophoresis was used as the reSolving technique. Four kinds Of en~yme components WerQ obtained from all the OEAE cellulose variants. Each of these four kinds of enzyme components was dissociated to further enzyme

units when subjected to polyacrylamide gel electrophoresis. These results argue against the isoenzymic nature of

these components. Further, no correlation was apparent with the variants obtained by DEAE cellulose column chromatography and polyacrylamide gel electrophoresis. There was also no correlation between the blood groups

and either of the two types of variants. So, the genetic nature of these DEAE cellulose variants is in doubt.

Results obtained from further investigations

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indicated that there were interactions between the isoenzymic components as well as between the enzymic

and non-enzymic membrane protein components. Such interactions may, at least partly, be responsible for the heterogeneity of erythrocyte acetylcholinesterase. However, the observed heterogeneity is obviously a very complicated phenomenon, which involves factors other